In general, a vehicle's seat belt is designed to protect the driver during a vehicle collision or the like to prevent injury. The seat belt, constructed with two or three supporting points, typically supports a driver's abdominal region and the chest. The buckling and unbuckling operation of the seat belt is normally manually performed. Therefore, there is a drawback in the conventional seat belt system in that the manual manipulation of the seat belt is inconvenient in emergency situations such as when escaping from the vehicle in the event of a vehicle collision or the like.